1. Field of the Invention
The present invention relates to a ventilator and a method for providing breathing support in EMG controlled mode.
2. Description of the Prior Art
Ventilators are used to support breathing in patients are unable to breathe or whose breathing function is insufficient. Traditionally two different modes have been used. If the patient shows some breathing activity a support mode such as pressure support or volume support mode can be used, in which the patient's attempts to inhale are used to trigger an inspiration phase in the ventilator. If the patient shows no breathing activity controlled mechanical ventilation mode must be used, in which a respiratory rate is determined without any input from the patient.
Recently, ventilators have been disclosed that are neurally controlled, that is, controlled in dependence on an electromyographic signal related to breathing. For example, U.S. Pat. No. 6,588,423 describes a ventilator that is controlled on the basis of an EMG signal from the diaphragm, referred to as an Edi signal (Electrical activity of the diaphragm). The EMG signal may be registered, for example by means of an esophageal catheter in a manner well known in the art.
In some cases the detected EMG signal does not reflect correctly the actual breathing phases of the patient. In such cases there may be a mismatch when the ventilator tries to supply air to the patient while the patient is trying to exhale.